Motor operated power transfer switch



May 19.65. P. G. SALERNO 3,185,790

MOTOR OPERATED POWER TRANSFER SWITCH Filed June 5, 1963 s Sheets-Sheet 1Inventor May 25, 1965 P. G. SALERNO MOTOR OPERATED POWER TRANSFER SWITCH5 Sheets-Sheet 2 Filed June 5, 1963 P J [mg entanaa a r 0 4/ 2 O.\\ I

y 25, 1965 P. G. SALERNO 3,185,790

- MOTOR OPERATED POWER TRANSFER SWITCH Filed June 5, 1963 3 Sheets-Sheet3 M if.

United States Patent 3,185 796 MOTOR OPERATED POW ER TRANSFER SWITI IPaul G. Salerno, Glen View, 11L, assignor to Vapor Corporation, Chicago,Ill., a corporation of Delaware Filed June 5, 1963, Ser. No. 285,747 4Claims. (Cl. MPG-92) The present invention relates to a power transferswitch. The invention relates more particularly to a power transferswitch utilizing an electric motor for the switch- 'ing operation, inwhich the operating parts, the contacts of the switch as Well as theoperating motor, are enclosed within a hermetically sealed casing, withcontact terminals projecting through the casing for appropriateconnection in circuit.

A broad object of the invention is to provide a power transfer switch ofthe foregoing character which is of extreme simplicity and consequentgreat reliability.

Another object is to provide a switch of the foregoing character whichis of compact design and utilizes an unusually small motor because ofits compactness.

Another object is to provide a switch of the character indicated havinga shorter transfer time than usual.

A further object is to provide a switch of the character indicated inwhich no power from the motor is required to hold the switch in eitherof opposite limit positions, the switch being retained in its limitpositions by a mechanical over-center device.

Another object of the invention is to provide a power transfer switch ofthe character noted in which a mechanical snap action is utilized in theswitching operation, thereby requiring only a low minimum motoroperating voltage.

A further object is to provide a switch in which a high contact force isestablished between the terminal contacts and a wiping action isestablished between the contacts in the closing operation, whereby onlya low millivolt drop is encountered through the contacts;

Still another object is to provide a switch incorporating yieldablebiasing means for accommodating overrun of the contact closing means,this same yieldablc biasing means being of strength substantiallygreater than the weight of the contacts and their holder, whereby toeliminate bounce and vibration of the contacts under surroundingvibration conditions.

Another object is to provide a switch having a movable contact carriagewhich moves between opposite limit positions in the switchingoperations, in which the parts supported and carried by the contactcarriage are distributed about its pivot axis, whereby to provide abalanced mass, and greater etliciency in operation.

Other objects and advantages of the invention will appear from thefollowing detailed description taken in conjunction with theaccompanying drawings in which:

FIG. 1 is a top view of the switch with the cover element of theenclosing casing removed, and veiwed approximately on line 1-1 of FIG.2;

FIG. 2 is a sectional view, on an enlarged scale, taken approximately online 2-2 of FIG. 1;

FIG. 3 is an exploded and distorted isometric view of the principaloperating parts of the switch, certain elements being shownsemi-diagrammatically, and certain elements being shown in section;

FIG. 4 is a small scale view similar to FIG. 1, but taken at a planeslightly lower than the plane of FIG. 1, this view showing theover-center means in a first limit position;

FIG. 5 is a view similar to FIG. 4, but showing the overcenter means inan intermediate position;

FIG. 6 is a view similar to FIGS. 4 and 5, but showing the over-centermeans in the opposite limit position;

FIG. 7 is an axial view of a portion of the representa- 3,185,790Patented May 25, I365 tion of FIG. 3, showing the contact carriage inswitchopen position;

FIG. 8 is a view similar to FIG. 7, but showing the contacts at themoment of engagement in the closing operation;

FIG. 9 is a. view similar to FIGS. 7 and 8, showing the contactsengaged, but with the contact carriage in a more advanced position andthe yieldable biasing means slightly compressed;

FIG. 10 is a View similar to FIGS. 7, 8 and 9, but with the contacts ina fully engaged position, and with the yieldable biasing means fullycompressed;

FIG. 11 is a detail view, partially in prespective, and

taken substantially at line 11-41 of FIG. 7, showing the contacts inopen position;

FIG. 12 is a view similar to FIG. 11, but with the contacts inengagement, and with the yieldable biasing means fully extended;

FIG. 13 is a view similar to FIGS. 11 and 12, but with the contacts infull force engagement, and with the yieldable means fully compressed;

FIG. 14 is a View similar to FIG. 7, but showing a double throwarrangement; and

FIG. 15 is a diagram of the switch contacts and c011- tactors utilizedin the switch.

Referring in detail to the drawings, attention is directed first toFIGS. 1, 2 and 3 showing the switch embodying the features of thepresent invention substantially in its entirety. The switch structureillustrated includes a hermeticaliy sealed casing it) entirely enclosingall of the operating parts of the switch and preventing the propagationof sparks generated therein in the switching operation. The connectorelements 22 are incorporated in the casing, with extensions to theexterior, in a known manner.

Mounted in the casing is a top gear plate 24 and a bottom plate as,together constituting frame means or supporting means supportingsubstantially the remaining portions of the switch. The gear plate 24may be provided with strengthening ribs 23 radiating from a hub portion36 having an interior space 31 opening through one side at 32.

A contact carriage 34 is disposed concentrically in the casing andmounted for rocking movement in a manner to be described in detailhereinbelow. This contact carriage is preferably cylindrical in shape,defining a cavity 36 in which a motor 38 utilized for performing theswitching operations is friction-fitted for rocking movement therewith,the motor engaging a rearwardly or downwardly facing interior shoulder40, and secured in the cavity by compound material 42. At the lower endof the contact carriage is a plate 44 suitably secured therein andhaving an axial bearing extension 46 supported in a bearing opening 48in the bottom plate 26.

The drive shaft of the motor 38 is indicated at 50, and is connected, bymeans of a flexible coupling 52, to another shaft 54 mounted in suitablebearings 58 in the hub portion 301 of the gear plate 24. A pinion 5a issecured to the shaft 54 and meshes with a gear sector 60 of a movablemember 62 forming a portion of a mechanical overcenter device indicatedin its entirety at 64, the gear sector 69 projecting through the sideopening 32 into the interior space 31.

The gear plate 24 has an extension 24a which extends into the opening ofan annular plate 66. Extension 24a is coaxial with the bearing extension46 at the lower end of the contact carriage. These extensions supportthe contact carriage and thus the motor for rocking movements inopposite directions about the axis of the extensions 24a and 46 in theswitching operations as referred to hereinbelow.

Mounted on the upper end of the contact carriage 34,

I? and movable therewith, is the annular plate 66, secured thereto as bycap screws 63 one of which is shown in FIG. 2. This plate has a radialarm "it? (FIGS. 2 and 3) in which is mounted a post 72 extending througha clearance hole '74 in the gear plate 24, and into the confines of themovable member 62 of the over-center means 64.

The movable member 62 has a hub portion '76 trunnioned on a stub shaft78 fixed in the gear plate 24 and extending thereabove. This movablemember includes a pair of angularly spaced arms 89 merging into the gearsector 69. This gear sector, as will be noted, is on the order of 60angular dimension, and it has a range of movement in the neighborhood of45 in its operation described hereinbelow. The side arms titl areprovided with recesses 84 to facilitate engagement with opposite limitposts 36 adjacent the marginal edges of the switch casing. A compressionspring 83 is biased between the contact carriage post 72 which, as notedabove, extends into the space between the arms 8% and the gear sector 6tat a point on the latter indicated at 99, preferably adjacent the centerthereof.

Attention is directed again to the contact carriage 34 (FIG. 3) and tothe following description thereof concerning the switching operation.The contact carriage 34 includes arms 92 extending therefrom in oppositelateral directions with a substantial radial component. Mounted on andmovable with these arms are contacts 94- which engage stationarycontacts 96. The movable contacts 94 are incorporated in a contactassembly 93 described hereinbelow, while the contacts 96 are mounted onstationary means Tilt), shown diagrammatically in FIG. 3. Thissupporting means Ttitl may take any of various forms, such, for example,as a cylindrical member (FIG. 2) surrounding the contact carriage 34 andsupported by the top gear plate 24 and bottom plate 26 in any suitablemanner, such as indicated at the points Till. The supporting means 1%,or contact housing (FIG. 2) supports a plurality of blocks MP2, on whichthe contacts 96 are mounted, there being four on each side, only thoseon one side being shown in FIG. 2. FIG. 2 also shows two arms 92 andassemblies 98 thereon, each bearing two of the contacts 94. Forsimplicity in illustration, a portion of the elements of FIG. 2 havebeen omitted from FIG. 3, the contact carriage 34 in FIG. 3 being of substantially half its full length and being shown as if taken at line 33of FIG. 2.

Each contact assembly 98, herein sometimes designated a contactor forconvenience, includes a plate 196 supporting the movable contacts 94 andsecured to the corresponding arm Q2 by means of a contact holder 1G8.This contact holder 10$ is preferably in the form of a shaped metalpiece having hooks 110 straddling the side edges of the plate 106 andengaging the under surface thereof, and hooks 112 extending transverselyto the hooks lltl straddling the side edge of the arm 92.

interposed between the plate 195 and the arm 92 is a stainless steelleaf spring 114 (FIGS. 11-13) having a central bowed portion 116engaging the arm Q2 and fiat end surfaces 118 engaging the plate 106.The plate 1% has sliding engagement with the hooks 1m to enable it tomove toward and from the arm 92 in the switch closing and openingmovements. When the contact holder is in switch-open position, with thecontacts 94 and 96 separated, the leaf spring 116 biases the plate 166and the contacts 9 thereon away from the arm 92, and when the contactholder moves to switch closing position (counterclockwise, FIGS. 7-10)with consequent engagement between the contacts 94- and 96, the leafspring 116 yields under the continued movement of the arm 92, asrepresented by the relative positions illustrated in FIGS. 12 and 13.Certain specific characteristics of the contacts and leaf spring will bereferred to again hereinbelow.

The blocks 16 2 bearing the stationary contacts 9 5 are provided withterminal extensions 12% adapted for connection with connector el mentsin a known manner.

The electric motor 38 is providid with connecting leads 122 which, inorder to eliminate flexing connections, are contained within the contactcarriage 34 and connected with circuit connections leading through thecontact carriage to appropriate ones of the contacts 94-.

Assuming a starting position of the contact carriage 34 as representedin FIG. 3, with the switch in open position, the motor 38, uponenergization thereof, rotates the drive shaft 56 thereof in a clockwisedirection as viewed in FIG. 3 from the lower right. This rotation isrepresented by the arrow 124 in FIG. 4, the pinion S6 rotatingcounterclockwise as viewed in the latter figure. This pinion meshingwith the gear sector 60 rotates or rocks the latter in clockwisedirection as indicated by the arrow 126. The movable member 62 thereforerocks from one limit position shown in FIG. 4 toward the opposite limitposition shown in FIG. 6, and in the course of this movement, as itreaches the approximate position shown in FIG. 5, the contact carriagepost 72 swings over center represented by the line 123, carrying thecontact carriage with it, thus moving the contacts 94 into engagementwith the stationary contacts 96, closing the switch. The switch ingoperation also interrupts the driving current to the motor 38, but itremains established until the overcenter means becomes effective, whenthe compression spring 83 continues to move the member 62 in clockwisedirection (FIGS. 3-6) until it reaches its opposite limit position aslimited by the corresponding limit post 86. This continued movement ofthe member 62 continues to rotate the drive shaft of the motor until themember 62 reaches the opposite limit position.

The movement of the contact carriage 34 is a snap action movement, thecontacts remaining open until the post 72 snaps past the line 128 andthen abruptly closing.

In the switch opening operation, the motor is driven in the oppositedirection, and the various parts move toward and assume their oppositepositions in the manner described above in connection with the switchclosing operation. In the switch opening operation also, the contactcarriage 34 operates through a snap action movement.

The illustrations of FIGS. 2 and 3 indicate a single throw switch, butit will be understood that the construction is readily adaptable to adouble throw switch. Such a switch is indicated in FIG. 14, where thearm 92 is provided with a contact assembly 98 on each of opposite sides,and a second set of contacts 96 is provided for engagement by thecorresponding movable contacts 94 when the contact carriage 34 is inopposite position, or that corresponding to that indicated in FIG. 3.FIG. 15 includes a diagram of contacts adapted for incorporation in theswitch described above, that is, three pairs of stationary contacts 96are provided in a single pole arrangement; also included are motorreversing contacts 96a and 96b. The opposed contacts 96a and 96b areutilized for reversing the voltage of the motor 38 for driving thelatter in each of opposite directions in alternate operations of theswitch. This is accomplished by application of electrical power to theproper terminals denoted in the lower left corner of FIG. 15.

Attention is directed to FIGS. 7 to 13 for a representation of thespecific contact-closing and contact-opening movements. The plate 1% asnoted above is mounted on the arm 92 for movement toward and from thearm. This plate is also mounted for limited angular movement relative tothe direction of its switch closing movement. As shown best in FIG. 7,the contact assembly 98 is disposed at a substantial angle to theclosing movement thereof, the dot-dash line 13%) indicating thedirection of closing movement, and the line 132 the angular position ofthe contact assembly 98. After engagement of the contacts in the closingmovement of the switch, the control assembly moves angularly toward thedirection of movement and causes a wiping action between the movable andstationary contacts. This action is indicated in FIG. 8 where thecontacts are shown in the initial step of engagement and the angulardistance between the lines 130 and 132 is slightly reduced. As theswitch closing operation continues, as represented in FIG. 9, the leafspring 116 is partially compressed, and the movable contacts 94 havemoved angularly to a position in which they extend more nearly in thedirection of closing movement. In the final position represented in FIG.10, in which the switch is in full-closed position, the contacts aremoved to a position in which they extend substantially in the directionof closing movement. The Wiping action caused by this movement of themovable contacts greatly increases the electrical contact engagementbetween the contacts. This wiping action and the compression of the leafspring 116 described above are accomplished in the latter portion of themovement of the contact carriage 34 through the action of thecompression spring 88, rather than the driving force of the motor. Thesnap action of the over-center device overtakes the driving force of themotor in the latter portion of the movement and therefore the torquerequired of the motor for the switching operation is at a minimum, beingmerely that necessary to move the movable member 62 to over-centerposition, and is not utilized for directly moving the contact carriagein the switch opening and switch closing movements.

The force of the compression spring 116 is preferably many times greaterthan the weight of the plate 106 and the movable contacts 94 thereon, soas to prevent vibration or chattering of the plate 106 in surroundingvibration conditions. Preferably, this force of the leaf spring relativeto the weight of the movable element is on the order of 80 to 1.

While I have disclosed herein a certain preferred form of the invention,it will be understood that changes may be made therein within the scopeof the appended claims.

I claim:

1. A switch of the character disclosed comprising, in combination,mounting means, a set of stationary contacts supported by said mountingmeans, a contact carriage having contactor means thereon and movablebetween opposite positions in which the contactor means is respectivelyin and out of electrical engagement with said contacts, a mechanicalovercenter mechanism including a member movable between opposite limitpositions, said over-center mechanism also including a compressionspring reacting between said movable member and contact carriage, areversible electric motor having driving connection with said movablemember and operable for moving the latter to over-center position ineach direction toward its opposite limit position, said movable memberbeing operable, acting through said compression spring for moving saidcontact carriage to its opposite position in response to its ownmovement to over-center position,

said contact carriage being rockable about a central longitudinal axis,the stationary contacts including contacts on radially opposite sides ofthe contact carriage and the contactor means including movable contactson each of radially opposite sides of the contact carriage positionedfor engaging respective ones of said stationary contacts, whereby thecontact carriage is balanced by distribution of mass symmetricallyaround said axis, and said motor being mounted within and carried bysaid contact carriage.

2. A switch structure comprising, in combination, supporting means, acontact carriage mounted in the supporting means for rocking movementabout a central longitudinal axis to opposite limit positions,stationary contacts mounted on said supporting means on each of radiallyopposite sides of said contact carriage, contactors mounted on saidcontact carriage on radially opposite sides thereof and movable into andout of engagement with respective stationary contacts in response tomovement of said contact carriage to its opposite positions, saidcontact carriage including a central cavity, a reversible motor mountedin said cavity and carried by said contact carriage, a mechanicalover-center device including a movable member pivoted on said supportingmeans and movable between opposite limit positions, said movable memberhaving a gear sector on a swinging end, said contact carriage having aneccentric element extending axially to a position within the confines ofsaid movable member, said extension being movable, in response torocking movement of said contact carriage, to respective positions onopposite sides of a line passing through the axis of movement of saidmovable member and bisecting the angle of movement thereof, acompression spring biased between said extension and said movable memberat a point on the latter adjacent the angular center thereof, and apinion driven by said motor, concentric with said central longitudinalaxis, and in mesh with said gear sector.

3. The invention set out in claim 2 in which circuit for controllingsaid motors is provided, and it includes connections for said motorfixed to said contact carriage and connected through certain of saidcontacts and contactors.

4. The invention set out in claim 2 in which all of the stated elementsare enclosed in a hermetically sealed casing, and circuit elements areincluded, connected with said contacts and leading through the wall ofsaid casing.

References Cited by the Examiner UNITED STATES PATENTS 560,766 5/96 VanVleck 200-92 2,116,075 5/3 8 Lenhart 200-92 2,924,685 2/60 Burch200--104 BERNARD A. GILHEANY, Primary Examiner. ROBERT K. SCHAEFER,Examiner.

1. A SWITCH OF THE CHARACTER DISCLOSED COMPRISING, IN COMBINATION, MOUNTING MEANS, A SET OF STATIONARY CONTACTS SUPPORTED BY SAID MOUNTING MEANS, A CONTACT CARRIAGE HAVING CONTACTOR MEANS THEREON AND MOVABLE BETWEEN OPPOSITE POSITIONS IN WHICH THE CONTACTOR MEANS IS RESPECTIVELY IN AND OUT OF ELECTRICAL ENGAGEMENT WITH SAID CONTACTS, A MECHANICAL OVERCENTER MECHANISM INCLUDING A MEMBER MOVABLE BETWEEN OPPOSITE LIMIT POSITIONS, SAID OVER-CENTER MECHANISM ALSO INCLUDING A COMPRESSION SPRING REACTING BETWEEN SAID MOVABLE MEMBER AND CONTACT CARRIAGE, A REVERSIBLE ELECTRIC MOTOR HAVING DRIVING CONNECTION WITH SAID MOVABLE MEMBER AND OPERABLE FOR MOVING THE LATTER TO OVER-CENTER POSITION IN EACH DIRECTION TOWARD ITS OPPOSITE LIMIT POSITION, SAID MOVABLE MEMBER BEING OPERABLE, ACTING THROUGH SAID COMPRESSION SPRING FOR MOVING SAID CANTACT CARRIAGE TO ITS OPPOSITE POSITION IN RESPONSE TO ITS OWN MOVEMENT TO OVER-CENTER POSITION, SAID CONTACT CARRIAGE BEING ROCKABLE ABOUT A CENTRAL LONGITUDINAL AXIS, THE SIDES OF THE CONTACTS INCLUDING CONTACTS ON RADIALLY OPPOSITE SIDES OF THE CONTACT CARRIAGE AND THE CONTACTOR MEANS INCLUDING MOVABLE CONTACTS ON EACH OF RADIALLY OPPOSITE SIDES OF THE CONTACT CARRIAGE CONTACTS, FOR ENGAGING RESPECTIVE ONES OF SAID STATIONARY CONTACTS, WHEREBY THE CONTACT CARRIAGE IS BALANCED BY DISTRIBUTION OF MASS SYMMETRICALLY AROUND SAID AXIS, AND SAID MOTOR BEING MOUNTED WITHIN AND CARRIED BY SAID CONTACT CARRIAGE. 